Image development station

ABSTRACT

A development station is provided whereby an electrostatic image moving along a horizontal path is developed by a developer which consists of a mixture of toner particles and carrier beads. The developer is dispensed across the electrostatic image as it moves along its path and agitated by a barrier extending across the path at a height from the image path to permit passage of toner particles sticking to the electrostatic image but for the most part prohibiting passage of carrier beads. This barrier may include a variety of shapes such as a flat blade extending at an angle across the developer, a curved blade, a counter-rotating paddle wheel, a plurality of blades wherein the first blade is at a height to allow both toner and carrier beads to pass thereunder and a second blade is at a height to permit only toner particles adhering to the electrostatic image to pass thereunder, or the blade may be comb-shaped so that a portion of the excess developer and carrier beads may move along with the electrostatic image. The blade can be used to provide solid area development by applying a potential thereto.

United States Patent Altmann 51 Nov. 7, 1972 s41 IMAGE DEVELOPMENT STATION [72] Inventor: Conrad Altmann, Rochester, N.Y.

[73] Assignee: Eastman Kodak Rochester, N.Y.

Nov. 12, 1969 Company,

221 Filedz 211 Appl. No; 875,818

[52] US. Cl. ..118/637, 1l7/17.5, 355/3 [51] Int. Cl ..B05b 5/02, G03g 13/00 [58] Field of Search .....'ll8/637; ll7/17.5',96/l, 1.4,

96/1 A, l C, 15 D, l E, 95/1 A; 355/3 Hodges ..1 18/637 DEVELOPER STATION 9 I 2.. VIBRATOR 24 2 6- Primary Exam inerJamesKee Chi Attorney-Robert W. Hampton and Gary D. Field [5 7] ABSTRACT A development station is provided whereby an electrostatic image moving along a horizontal path is developed by a developer whichconsists of a mixture of toner particles and carrier beads. The developer is dispensed across the electrostatic image as it moves along its path and agitated by a barrier extending across the path at a height from the image path to permit passage of toner particles sticking to the electrostatic image but for the most part prohibiting passage of carrier beads. This barrier may include a variety of shapes such as a flat blade extending at an angle across the developer, a'curved blade, a counter-rotating paddlewheel, a plurality of blades wherein the first blade is at a height to allow both toner and carrier beads to pass thereunder and a second blade is at a height to permit only toner particles adhering to the I electrostatic image to pass thereunder, or the blade may be comb-shaped so that a portion of the excess developer and carrier beads may move along with the electrostatic image. The blade can be used to provide solid area development by applying a potential thereto.

13 Claims, 8 Drawing Figures 22 IMAGE FORMING STATION TRANSFER CLEANlNG STATlON u STATION,

PATENTEDIIHY 11912 3.702.108

&

' DEVELOPER STATION ,22 IMAGE FORMING STATION TRANSFER CLEANING STATlON STATION FIGJ CONRAD ALTMANN INVENTOR.

FIGA BY A. @4464 ATTORNEYS PATKNTED 3.702.108 sum 2 0r 2 CONRAD ALTMANN INVENTOR.

KW M ATTORNEYS IMAGE DEVELOPMENTSTATION BACKGROUND OF-THE INVENTION 'ways, one of which isca'scade development. In cascade development, a developer comprising a mixture of v resinous powder particles and carrier beads is allowed to flow by gravity across a photoconductive member which is inclined to tone an electrostatic image thereon. One disadvantage of such devices is that in order to assure adequate toning the photoconductive member must move at a. relatively slow rate ora sub- I stantially long development path must be used to assure that allareasof the image receive sufficient -toner. Neither alternative is desirable since the trend is toward more compact, higher speed office equipment.

.Some apparatus, such as that disclosed in US. Pat.- No. 3,239,465 to-Rheinfrank, which issuedMarf'S, 1966, provide means for moving'developer material laterally across a photoconductive member to tone .an image. Inthis, the photoconductive memberis tipped so that gravity causes the developer material to flow .from one side to the other. Such device is speedlimited due to the reliance upon gravity'forthe. lateral movement of developer material. InCanadian Pat. No. 617,721 which issued Apr. 4, 1961 a means isprovided for vibrating a photoconductive member to cause uniform distribution of toneracrosszan image'thereon.

SUMMARY OF THE INVENTION a In accordance with the present invention an electrostatic latent image on a photoconductive member is moved along a horizontalpath and is-developed by depositing developermaterial across the path of move- 'ment of the photoconductive member. Downstream from the point at which developer is applied a barrier member is provided which causes lateral movement of the developer material across the electrostaticimage to enhance development thereof. This barrier ortbladeis spaced from the path of the elctrostatic' image a distance sufficient to permit toner to pass thereunder but prevents carrier beads from passing thereunder. Many of these carrier beads are forced laterally across the photoconductive member because of the shape and orientation of the barrier sothat other toner particles clinging to them will contact other portions of the electrostatic image. The barrier develops a standing wave member or it may curve back over the standing wave so that the standing wavemoves in a circular motion. Alternatively, a counter-rotating paddle wheel rotates in a direction to I flip toner and carrier particles in a direction opposite that in which the photoconductive member is moving but is spaced above. In further embodiments a plurality of barrier members can be provided which are positioned diagonally-across the path of movement of the photoconductive materials so that one barrier member causes developer material to move laterallyacross the electrostatic image in onedirection and the other barrier causes development material to move laterally across the electrostatic image in the opposite direction to enhance development. In still a further embodiment barriers can be provided wherein developer is causedto'move from the centerof the electrostatic image laterally out to opposite edges thereof. Furthermore, a first barrier can be spaced at a distance from the photoconductive material so that further embodiment includes a barrier member which is serrated or has a comb-shaped lower edge forming teeth between which both toner particles and a portion of the carrier beads may pass after moving laterally to of agitated developer material to assure more complete development. A vibratoralso'can beused in conjunction with the barrier to agitate the photoconductive member to further improve development. vantageously, developer initially need not beuniformly distributed across the photoconductive member but can be dropped at one lateral edge thereof so that the barrier distributes it as the photoconductive member thereunder.

. The barrier may take many forms. It can be a flat blade extending diagonally across the photoconductive get around the teeth.

Each of the foregoing described devices normally provides fringe development. However, solid area development can be accomplished by applying a potential to the barrier.

Additional advantages of this invention will be readi Iy apparent from the description which follows, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammaticside elevation, partly in section for clarity of illustration, showing a preferred embodiment of the developing station of this invention;

FIG. 2 is an enlarged horizontal section, taken along line 2-2 of FIG. 1, illustrating movement of toner across a photoconductive member;

FIG. 3 is a fragmentary side elevation showing an alternative barrier; I

FIG. 4 is a fragmentary side elevation similar to FIG. 3, showing a further alternative barrier comprising a paddle wheel;

FIG. 5 is a, top plan view of a photoconductive member, similar to FIG. 2 but showing the use of two barriers mounted at divergent angles to each other;

FIG. 6 is a fragmentary side elevation of the barriers of FIG. 5;

FIG. 7 is a fragmentary top plan view, similar to FIG.

5 showing barrier members which cause toner to move DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with this invention a web of photoconductive material such as endless belt 2 may be mounted between a pair of spaced rollers 4 and 6, as shown in FIG. 1. Conveniently, the photoconductive belt 2 may be driven in the direction indicated by the arrows, by drive means not shown, past an image forming station 8 whereat an electrostatic latent image will be formed on the photoconductive material by electrostatically charging the material and imagewise exposing it in any conventional manner. e After the electrostatic image is formed a portion of photoconductive belt 2 moves the image along a substantially horizontal path past a development station 10 which deposits developer material 12 across the belt as the, belt moves along asubstantially horizontal path. conveniently, developer 12 may comprise a mixtureof carrier beads and resinous toner particles. The-toner particles will receive a proper triboelectric charge when the mixture is agitated due to movement within developer station 10 Developer 12 is caused to form a standing'wave' 14, as shown in FIG. 1 by barrier 16 mounted diagonally across the path of belt'2. Movement of belt -2 causes the standing wave 14 to be agitated to assure more complete development of the electrostatic image. Barrier 16 causes the toner to move laterally across the belt in addition to being agitated. This relative movementbetween the electrostatic image on belt 2 and the toner particles assures that toner contacts each portion of the image so that it is adequately toned.

Advantageously, barrier 16 may be spaced from the path of photoconductive belt 2 at a distance which permits toner particles to pass thereunder but prevents the passage of 'most carrier beads. The direction of photoconductive belt 2 is reversed by roller 4 and any excess toner particles and carrier beads fall into an incline 18 of developer station 10. Other toner and car- 'rier particles which are forced off to the side of the belt by barrier 16 will also fall down onto incline 18. The developer will be collected at the lower end of incline 18 to be raised by a conveyor 20 to be dispensed through slot 22 onto photoconductive belt 2. If desired, a vibrator 24 may be provided as part of the developing station to enhance toning. After development, the toner image is carried by photoconductive belt 2 past a transfer station 25 where it is transferred onto a suitable receiver, not shown. Finally, the belt moves past a cleaning station 26 wherein the residual toner particles contained thereon are removed. Also, it can include an erase lamp (not shown) to neutralize any remaining charge on the photoconductive belt. The cycle is then repeated.

The system just described was a fringe development system. In order to develop solid areas a potential may be applied to barrier 16 through circuit 27 which includes a potential source 28 and a switch 29 which may be optionally closed when solid area development is required. In such a situation, the carrier particles must be made of a conductive rather than an insulative material.

An alternative embodiment is shown in FIG. 3 wherein a barrier member 30 has a curved configuration as shown so that the standing wave 32 of toner will be thrown back upon itself to further agitate the toner and enhance development. As in the previous embodiment, barrier 30 is spaced above the path of photoconductive belt 2 a distance sufficient to permit only toner particles to pass thereunder.

A further alternative embodiment is shown in FIG. 4, wherein a barrier 34 inthe form of a paddle wheel is provided which is counter-rotating, i.e., it rotates in the opposite direction to the path of movement of photoconductive web 2. Portions of a standing wave 36 formed by the paddle wheel are flipped'in an upstream direction to provide additional agitation to enhance development. The blades 38 of the paddle wheel are spaced from the path of photoconductive web 2 a distance sufficient to permit toner particles adhering to the electrostatic image to pass thereunder.

A further alternative embodiment is shown inFIGS. 5 and6 wherein a pair of barriers 40 and 42 extend laterally across photoconductive belt 2 at converging angles to each other so that a standing wave 44 formed in front of barrier 40 is forced toward one lateral edge of belt 2 and standing wave 46 formed by barrier 42 if forced to the opposite lateral edge of belt 2. Conveniently, the lower edge of barrier 40 is spaced above the path of photoconductive web 2 a distance sufficient that both toner particles and some carrier particles may pass thereunder. Barrier 42, however, is spaced closer to the path of photoconductive web 2 so that substantially only toner particles can pass thereunder. With this arrangement even greater agitation and hence improved development of the electrostatic image on photoconductive belt 2 can be obtained.

A further embodiment as shown in FIG. 7 wherein a pair of barriers 48 and 50 which each comprise two legs which angle downstream from the center so that developer material deposited at the center of photoconductive belt 2 will be caused to move outwardly to the opposite lateral edges thereof. As in the embodiment of FIGS. 5 and 6, the lower edge of barrier 48 may be spaced from photoconductive web 2 a distance greater than that of lower edge of barrier 50 so that both toner particles and carrier particles may pass under barrier 48. Barrier 50, however, will be spaced only-a sufficient distance to allow substantially only toner particles to pass thereunder.

A further embodiment as shown in FIGS wherein a barrier 56 is provided which has a serrated lower edge 58 so that toner particles can pass thereunder and a portion of the carrier'particles can pass therethrough. Barrier 56 will also create a standing wave which enhances development. Conveniently, it may be positioned at an angle across the path of photoconductive web 2 so that the development material is caused to move laterally across the photoconductive web to one side thereof.

From the foregoing, the advantages of this invention should be readily apparent. A development station has been provided which does not rely on gravity to cause relative movement between the developing material and the electrostatic image. Instead, a variety of barriers are provided which agitate developer material placed on a substantially horizontally moving photoconductive web having an electrostatic image thereon. These barriers cause the developer to move laterally across the web to enhance development of the electrostatic image. The developer need not be uniformly distributed across the photoconductive member initially, but can be deposited at one edge so that it is moved across the photoconductive member by the barrier. In addition, a vibrator may be provided in combination with the barrier to further enhance development. Furthermore, if the solid area of development is desired apotential may be applied to the barrier for this purpose.

' The invention has been described indetail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

lclaim: I I

1. An apparatus for developing'a latent electrostatic image by means of developer which includes toner particles and carrier particles, said developing apparatus comprising: p

means for placing said developer on said electrostatic image;

means for moving said electrostatic image along a substantially horizontal path; and

means. for causing relative movement of said developer with respect to said image as said image is moved along said path so that-said toner particles are electrostatically attracted to said electrostatic image. I V

2. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: v i

a straight barrier extending across the path of said electrostatic image to create a standing wave of developer across said path and spaced therefrom a sufficient distance to permit'toner particles adhering to said electrostatic image to pass thereunder but preventing substantially all carrier particles from passing thereunder.

3. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: I

- static image to create a standing wave of developer across said'path and spaced therefrom a distance sufficient to allow toner particles adhering to said electrostatic image to pass thereunder but preventing carrier particles from passing thereunder, and said barrier having a surface which curves back over said standing wave to cause agitation of said developer.

4. A developing apparatus as claimed in claim 1 whereinsaid means for causing relative movement includes:

a barrier extending at an angle across said toner image path to create a standing wave of developer across said path and spaced therefrom a sufficient distance to permit toner adhering to said electrostatic image to pass under said barrier but causing substantially all of said carrier particles to move laterally across said image and to be discharged over a side edge of said image.

5. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes:

a barrier extending across said toner image path and spaced therefrom, said barrier having a lower edge with a comb-shaped surface which inhibits passage therethrough of some of said carrier particles and permits passage of other said carrier particles.

6. A developing apparatus, as claimed in claim 1,

further including:

barrier extending across the path of said electroa ,vibrator adjacent said barrier to enhance toning of said electrostatic image.

7. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: 1

a paddle wheel extending across said toner image path and'rotatable in a direction. to-cause toner and carrier particles to be flipped in a direction opposite to the direction of movement of said electrostatic image.

8. A developing apparatus as claimed in claim 1 wherein said means for causing relative movementincludes:

a first barrier extending across said electrostatic image path to form a first standing wave of developer across said path and spaced from said image a distance sufficient to permit both toner and carrier particles to pass thereunder;-and

a second barrier extending across said electrostatic image path to form a second standing wave of developer across said path and spaced from said path a distance sufficient to permit toner particles adhering to said electrostatic image to pass thereunder but substantially preventing passage of carrier particles thereunder.

9. A developing apparatus as claimed in wherein:

said first barrier is positioned to direct developer to one edge of said electrostatic image; and

said second barrier is positioned to direct developer toward the opposite edge of said electrostatic image. i

10. A developing apparatus as claimed in claim 8 wherein:

said first and second barriers are each constructed to direct said developer from the center of said electrostatic image toward opposite edges thereof.

11. An apparatus for developing a substantially horizontal latent electrostatic image with developer said apparatus comprising:

means for placing said developer on said electrostaticimage;

a substantially horizontal barrier; and

means for causing relative movement between said electrostatic image and said horizontal barrier to cause lateral movement of said developer across said image.

12. In an electrophotographic apparatus for forming and toning an electrostatic image with developer, wherein said apparatus comprises:

a photoconductive web mounted for movement along a path;

means for forming an electrostatic image on said web;

a developing station for toning said. electrostatic image to form a toner image; A

a transfer station fortransferring said toner image from said web to a receiver; and

a cleaning station for cleaning residual toner particles from said web; the improvement comprising:

means for moving said web along a horizontal path at said developing station; and

means for moving said developer laterally across said electrostatic image as said web moves along said horizontal path.

claim 8,

v 13. An apparatus for developing a substantially means for placing developer on the electrostatic horizontal latent electrostatic image with developer, image adjacent said barrier; and

said apparatus comprising:

means for supporting an electrostatic image in a substantially horizontal position; a substantially horizontal barrier for controlling movement of the developer on the electrostatic image; f

means for causing relative movement between said electrostatic image and said horizontal barrier to cause said barrier to control movement of the developer on the electrostatic image.

UNITED, STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,702,108 Dated November 7 1077- inventofls) Conrad Altmann It iscertified that error a ppears in the above-identified patent and that said Letters Patent are hereby corrected as shown below Column 5 line 64,}"1" should reacl 2 Silg'I ied ehd s eel d this 1st day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. r I ROBERT GOTTSCHALK Afctesting Officer I v Commissioner of Patents FORM P071050 (10-59) USCOMM-DC 60376-P69 RINTING OFFICE 190s o-sss-su 1% U.S. GOVERNMENT P UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 702 108 Dated November 1 1 07?- Inventor) Conrad Altmann It is certified that error appears in the aboveidentified patent and that said Letters Patentere hereby corrected as shown below:

Column 5, line 64, "1" should read 2 Signed and sealed this 1st day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR.

ROBERT GOTTSCHALK Attesting, Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM'DC 60376-P59 l U.S. GOVERNMENT PRINTING OFFICE I969 0-366-334, 

1. An apparatus for developing a latent electrostatic image by means of developer which includes toner particles and carrier particles, said developing apparatus comprising: means for placing said developer on said electrostatic image; means for moving said electrostatic image along a substantially horizontal path; and means for causing relative movement of said developer with respect to said image as said image is moved along said path so that said toner particles are electrostatically attracted to said electrostatic image.
 2. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: a straight barrier extending across the path of said electrostatic image to Create a standing wave of developer across said path and spaced therefrom a sufficient distance to permit toner particles adhering to said electrostatic image to pass thereunder but preventing substantially all carrier particles from passing thereunder.
 3. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: a barrier extending across the path of said electrostatic image to create a standing wave of developer across said path and spaced therefrom a distance sufficient to allow toner particles adhering to said electrostatic image to pass thereunder but preventing carrier particles from passing thereunder, and said barrier having a surface which curves back over said standing wave to cause agitation of said developer.
 4. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: a barrier extending at an angle across said toner image path to create a standing wave of developer across said path and spaced therefrom a sufficient distance to permit toner adhering to said electrostatic image to pass under said barrier but causing substantially all of said carrier particles to move laterally across said image and to be discharged over a side edge of said image.
 5. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: a barrier extending across said toner image path and spaced therefrom, said barrier having a lower edge with a comb-shaped surface which inhibits passage therethrough of some of said carrier particles and permits passage of other said carrier particles.
 6. A developing apparatus, as claimed in claim 1, further including: a vibrator adjacent said barrier to enhance toning of said electrostatic image.
 7. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: a paddle wheel extending across said toner image path and rotatable in a direction to cause toner and carrier particles to be flipped in a direction opposite to the direction of movement of said electrostatic image.
 8. A developing apparatus as claimed in claim 1 wherein said means for causing relative movement includes: a first barrier extending across said electrostatic image path to form a first standing wave of developer across said path and spaced from said image a distance sufficient to permit both toner and carrier particles to pass thereunder; and a second barrier extending across said electrostatic image path to form a second standing wave of developer across said path and spaced from said path a distance sufficient to permit toner particles adhering to said electrostatic image to pass thereunder but substantially preventing passage of carrier particles thereunder.
 9. A developing apparatus as claimed in claim 8, wherein: said first barrier is positioned to direct developer to one edge of said electrostatic image; and said second barrier is positioned to direct developer toward the opposite edge of said electrostatic image.
 10. A developing apparatus as claimed in claim 8 wherein: said first and second barriers are each constructed to direct said developer from the center of said electrostatic image toward opposite edges thereof.
 11. An apparatus for developing a substantially horizontal latent electrostatic image with developer said apparatus comprising: means for placing said developer on said electrostatic image; a substantially horizontal barrier; and means for causing relative movement between said electrostatic image and said horizontal barrier to cause lateral movement of said developer across said image.
 12. In an electrophotographic apparatus for forming and toning an electrostatic image with developer, wherein said apparatus comprises: a photoconductive web mounted for movement along a path; means for forming an electrostatic image on said web; a developing station for toning said electrostatic imaGe to form a toner image; a transfer station for transferring said toner image from said web to a receiver; and a cleaning station for cleaning residual toner particles from said web; the improvement comprising: means for moving said web along a horizontal path at said developing station; and means for moving said developer laterally across said electrostatic image as said web moves along said horizontal path.
 13. An apparatus for developing a substantially horizontal latent electrostatic image with developer, said apparatus comprising: means for supporting an electrostatic image in a substantially horizontal position; a substantially horizontal barrier for controlling movement of the developer on the electrostatic image; means for placing developer on the electrostatic image adjacent said barrier; and means for causing relative movement between said electrostatic image and said horizontal barrier to cause said barrier to control movement of the developer on the electrostatic image. 